Difference between float and double java

• Float data type in java is represented in 32 bits, with 1 sign bit, 8 bits of exponent, and 23 bits of the mantissa

• Where as Double is  is represented in 64 bits, with 1 sign bit, 11 bits of exponent, and 52 bits of mantissa.
• Default value of float is 0.0f.
• Default value of double is 0.0d.
• Floating points numbers also known as real numbers and in java there are two types of floating point one is float and another one is double.






• Float specifies single precision and double specifies double precision.
• According to the IEEE standards, float is a 32 bit representation of a real number while double is a 64 bit representation
• Normally we use double instead of float to avoid common overflow of range of numbers
• Check below diagram for width and range of float and double data types

 When do you use float and when do you use double:

• Use double data type for all your calculations and temp variables. 
• Use float when you need to maintain an array of numbers - float[] array (if precision is sufficient), and you are dealing with over tens of thousands of float numbers.
• Most of the math functions or operators convert/return double, and you don't want to cast the numbers back to float for any intermediate steps.

How many significant digits have floats and doubles in java?

• In java float can handle about 7 decimal places.
• And double can handle about 16 decimal places

Program #1: write a java example program which explains differences between float and double in java

1. package com.instanceofjava.floatvsdouble;
2. 
   
3. import java.math.BigDecimal;
4. 
   
5. 
   
6. public class FloatVsDouble {
7. 
   
8. /**
9. * @website: www.instanceofjava.com
10. * @category: float vs double in java with example program
11. */
12. public static void main(String[] args) {
14.     float  a=10.8632667283322234f;
15.     double b=10.8632667283322234f;
16.     
17.      System.out.println("float value="+a);
18.      System.out.println("double value="+b);
19.         
20.      b=10.8632667283322234d;
21.         
22.     System.out.println("float value="+a);
23.     System.out.println("double value="+b);
24.        
25. 
    
26. }
27. 
    
28. }

Output:

1. float value=10.863267
2. double value=10.863266944885254
3. float value=10.863267
4. double value=10.863266728332224